CHAPTER 7 - TOWARD PRACTICAL DEVICES

Abstract

This chapter discusses the characteristics of an ideal discrete bistable optical device, fundamental limitations, prospects of improving present devices by identifying giant nonlinearities, and utilization of the full power of optics by parallel processing. The characteristics of an ideal discrete bistable optical device are easily enumerated: (1) the device should be small, that is, of characteristic dimension of a micrometer, so that millions of them can be placed in a small volume; (2) it should be fast so that high-speed operations can be accomplished and the picosecond-pulse advantages of all-optical systems utilized; (3) it should be operable at room temperature to eliminate cryogenics and to increase its range of applicability, and finally, (4) it should be integratable to permit large numbers of interconnections insensitive to external perturbations. The use of bistable devices for two-dimensional image processing has different requirements. Large distortion-free devices are needed, but response times as slow as 1 ms are acceptable for some parallel-processing applications. Hybrid devices such as liquid-crystal light valves may be satisfactory for such applications if the cost can be made reasonable, but two-dimensional intrinsic devices may switch faster and be cheaper to construct.